Battery module technologies have been disclosed in which a battery pack that includes a plurality of battery cells is accommodated in a case. An example of a battery module using a battery pack is described in Patent Literature 1. In Patent Literature 1, a method is employed that makes use of the fact that cells expand during charging and in which a holding plate that is made of SUS and is an elastic member is pressed against a cell so as to secure the cell body and electrodes inside the cell by using the repulsive force against the expansive force.
Meanwhile, it has been confirmed by verification tests that among battery cells, the expansive force of next-generation lithium-ion cells during charging is reduced by approximately 20% to 30% compared with the conventional lithium-ion cells.
In the cell mounting method in Patent Literature 1, an elastic holding plate made of SUS presses against the cell in response to the expansive force of the cell during charging so as to secure the cell body and the electrodes inside the cell. Thus, a reduction in expansive force of next-generation cells leads to a reduction in force that presses against the cell, i.e., a reduction in the pressing force. Accordingly, in order to employ next-generation cells, there needs to be established a cell mounting method that results in an increased pressing force in accordance with required mechanical and environmental conditions.